A 2D (two-dimensional) display can not display a 3D (three-dimensional) image directly. The key to enable a viewer to see the 3D mage is to make a parallax between an image viewed by a left eye of the viewer and an image viewed by a right eye of the viewer, so that a stereoscopic effect is produced after the two images are fused by the viewer's brain.
3D display technologies include a naked eye type 3D display technology and a spectacle type 3D display technology, and the naked eye type 3D display technology has obtained more attentions than the spectacle type 3D display technology because it does not need to wear glasses. The gratings-type naked eye 3D display technology has become a common naked eye 3D display technology because of its advantages of simple process, small crosstalk and the like. With the development of 3D display technology, the display device that can realize the switch between 2D display and 3D display will be the mainstream product of the naked eye 3D display.